1. Technical Field
The present disclosure relates to a device for conveying continuous sheet media stored in a roll.
2. Related Art
A device for conveying sheet media is typically used in printers and other devices for processing paper or other sheet media. Such conveyance devices commonly convey continuous sheet media stored in a roll, for example, by means of roller pairs that hold the medium from above and below.
The ability to convey the processed medium precisely is desirable in such conveyance devices, and particularly in conveyance devices used in printers, in order to enable high quality processing (such as printing) of the conveyed medium (such as paper), and many different designs have been proposed.
For example, maintaining a constant load on the upstream side, known as back tension (the tension from the upstream side), of the paper feed rollers (delivery rollers) that feed the conveyed medium to the processing position has been proposed. When the conveyed medium is stored in a roll, such as when roll paper is used, for example, one method uses a tension lever to buffer the heavy load from the conveyed medium stored in a roll.
As another example, configurations that reduce this back tension to zero also exist. More specifically, this configuration constantly produces slack in the conveyed medium on the upstream side of the paper feed rollers (delivery rollers).
JP-A-2012-45876 discloses a continuous-paper transportation mechanism including a paper feed roller and a tractor. During printing, the paper feed roller is intermittently driven at a speed enabling conveying the continuous paper at a second feed distance per unit time and the tractor is intermittently driven synchronously to the paper feed roller at a speed enabling conveying the continuous paper at a first feed distance that is less than the second feed distance per unit time.
According to some embodiments, a conveyance device comprises a roll storage unit, a roll drive unit, a tractor, a slack detection unit, and a control unit. The roll storage unit is configured to store a continuous sheet conveyance medium in a roll, the roll drive unit delivers the conveyance medium stored in the roll storage unit toward the tractor, the tractor is configured to sequentially engage engaging parts in engagement holes formed along the length of the conveyance medium and is configured to convey the conveyance medium, stored in the roll storage unit, the slack defection unit is configured to detect slack in the conveyance medium between the roll storage unit and the tractor, and the control unit is configured to control the roll drive unit based on the detection value of the slack detection unit.
In some embodiments, in a conveyance method of a conveyance device, which includes a roll storage unit, a tractor, a roll drive unit, a slack detection unit, and a control unit, the roll storage unit stores a continuous sheet conveyance medium on a roll, and the engaging parts of the tractor are sequentially engaged in holes formed in the conveyance medium. The conveyance medium is delivered toward the tractor, and slack in the conveyance medium between the roll storage unit and the tractor is detected, and the roll drive unit is controlled based on the slack detected in the conveyance medium.
Some embodiments include a printing device that has the conveyance device described above, the printing device being configured to execute a printing process on the conveyance medium.
According to some embodiments, in a conveyance method of a conveyance device having a roll storage unit configured to store a continuous sheet conveyance medium in a roll, a tractor is configured to sequentially engage engaging parts in engagement holes formed along the length of the conveyance medium and convey the conveyance medium stored in the roll storage unit, a roll drive unit is configured to deliver the conveyance medium stored in the roll storage unit toward the tractor, and a slack detection unit is configured to detect slack in the conveyance medium between the roll storage unit and the tractor, the control method being configured to control the roll drive unit based on the detection value of the slack detection unit.
In some embodiments, the control method repeatedly drives the roll drive unit and delivers the conveyance medium toward the tractor when the slack detection unit does not detect slack in the conveyance medium; and stops the roll drive unit when the slack detection unit detects slack in the conveyance medium.